Our emphasis continues to focus on the bochemical mechanisms for morphogenesis in the vertebrate embryo. On the one hand, we utilize in vitro manifestations of in vivo morphogenesis as in the assay for cell adhesive specificity among the parts of the retina and tectum of the developing chick embryo. Enzymatic dissection with glycosidases suggest that a crucial cell surface component for this interaction is the Tay-Sachs ganglioside GM2. Use of specific antisera to this ganglioside and oligosaccharide fragments from all the major gangliosides reinforce this possibility. With the reagents at hand, and others in preparation, we plan to test the role of this ganglioside in neuromorphogenesis in vivo. To test the hypothesis that glycosyltransferases on cell surfaces might be carbohydrate-binding proteins that play some role in directing cell migration during morphogenesis, we are developing assays for teratogenesis in which sugar nucleotides and transferase inhibitors can be used. Finally, we are using the inducible glucuronyltransferase in chick embryo liver as a model membrane-bound protein and following its intracellular migration from the site of synthesis in the ER, to its site of action in the Golgi apparatus, to its ultimate site, the plasma membrane. This is being accomplished through the use of sub-cellular fractionation methods coupled with coupled enzyme biochemistry specific for the glycosyltransferases.